I have a 2009 model with the climate control.
It is impossible to have the exterior air get into the system without being significantly heated, even though the dials are sent to minimum temperature.
Is it possible that the air passing by the passage in from of the bulkhead is being heated up by the engine heat? the wall of the air chamber is a thin plastic. Or could it be that the engine bay rear rubber seal is not blocking the engine heat sufficiently?